1. Field of the Invention
The present invention relates to a processing rate monitoring apparatus which can be applied to a cell rate monitoring apparatus positioned on an ATM network (Asynchronous Transfer Mode network) to monitor a cell transfer rate for each connection.
2. Description of Related Art
Conventionally, in an approach employed for a cell rate monitoring means of the type related to the present invention, located on a transmission path, a counter is provided for each connection to check whether or not a cell passing through the connection violates a rate in each counter by updating the counter every cell transfer cycle.
Monitoring methods applicable to such cell rate monitoring means may be classified into two: (a) a method of measuring an interval between two arbitrary consecutive cells within cells transferred for the same connection; and (b) a method of measuring the number of cells transferred within a fixed time period for the same connection. Generally, any cell rate monitoring means relies on one or both of these methods.
However, since the conventional methods as mentioned above manage a cell transfer rate as an integer, when the cell transfer rate is extended to a cell interval or the number of cells, a problem on monitoring accuracy may inevitably arise in some cell rates to be monitored.
Particularly, when delay variations are taken into account, a tolerance should be increased by a varying portion for each of monitored cycles, so that the throughput cannot be monitored over a plurality of cycles without appropriate measures.
In addition, in an attempt to realize a monitoring apparatus which is capable of individually and dynamically setting a cell rate for each of a plurality of connections and allowing the setting within a band which continuously exists exponentially from a small value to a large value, the conventional methods as mentioned above would have to simultaneously perform a plurality of complicated monitoring processing, which are not taken into account in the conventional methods. Thus, it appears to be difficult to realize such a monitoring apparatus with the conventional methods.
The present invention has been made in view of the problem mentioned above, and is intended to propose a processing rate monitoring apparatus which is capable of more accurately monitoring a processing rate as compared with the prior art, and readily accommodating even an environment where a monitoring band extends over a wide range and a large number of objects are to be monitored.
To solve the problem mentioned above, a processing rate monitoring apparatus according to a first aspect of the present invention comprises (1) an appearance interval counter for counting a packet interval in a monitored connection at a real number level, and (2) determining means, operable each time a packet corresponding to a monitored connection is detected, to compare a count value on the appearance interval counter indicating a time elapsed from the previous detection to the detection of the packet, with an allowed value for an appearance interval calculated from a transmission rate of the monitored connection to determine the presence or absence of transmission rate violation in a current monitoring cycle.
As a consequence, a processing rate provided on the basis of a transmission rate is reflected to the count value of the appearance interval counter even to a real number value (a value including a decimal fraction), so that a round error of a count value, which has been possibly introduced in the past upon updating the count value, is reduced even if any value is required as a transmission rate for a monitored connection.
According to a second aspect of the present invention, a processing rate monitoring apparatus comprises (a) an appearance number counter for counting the number of packets appearing within a monitoring period at a real number level for a monitored connection, and (2) determining means, operable each time the lapse of the monitoring period is notified, to compare a count value of the appearance number counter indicating the number of packets newly counted within a current monitoring period with an allowed value for the number of appearing packets, calculated from a transmission rate of the monitored connection, to determine the presence or absence of transmission rate violation in the current monitoring period.
As a consequence, a processing rate provided on the basis of a transmission rate is reflected to the count value of the appearance number counter even to a real number value (a value including a decimal fraction), so that a round error of a count value, which has been possibly introduced in the past upon updating the count value, is reduced even if any value is required as a transmission rate for a monitored connection.
According to a third aspect of the present invention, a processing rate monitoring apparatus comprises (1) an appearance number counter for counting the number of packets appearing within a monitoring period at a real number level for a monitored connection, and (2) determining means, operable each time the lapse of the monitoring period is notified, to compare a count value of the appearance number counter indicating the number of packets newly counted within a current monitoring period with a delay variation allowed value to determine the presence or absence of transmission rate violation in the current monitoring period, wherein the delay variation allowed value is derived by adding delay variations to an allowed value for the number of appearing packets, and the allowed value is calculated from a transmission rate of the monitored connection.
As a consequence, the influence of delay variations occurring during the previous packet detection can be reflected to the count value of the appearance number counter, to which the processing rate is reflected to a real number level (a value including a decimal fraction), within the limits of delay variation allowed value. Thus, as long as a delay portion lies below the allowed value, the transmission rate can be monitored over a longer span.
According to a fourth aspect of the present invention, a processing rate monitoring apparatus comprises (1) event detecting means for notifying a monitored stream corresponding to an event appearing on a transmission path every transfer cycle, (2) a plurality of appearance interval counters each disposed for counting an event interval for a corresponding monitored stream, (3) a plurality of update timing generating means each corresponded to one or a plurality of the appearance interval counters for supplying an update timing signal each generated at different periods to the appearance interval counter placed in a corresponding relationship therewith, and (4) determining means, operable each time a monitored stream corresponding to a detected event is notified thereto from the event detecting means, to access an appearance interval counter corresponding to the monitored stream notified thereto, and to compare a count value of the appearance interval counter indicating a time elapsed from the previous detection to the detection of the event with an allowed value for an appearance interval calculated in consideration of an output period of the update timing and a processing rate of the monitored stream to determine the presence or absence of processing rate violation in a current monitoring cycle.
As a consequence, the updating of the appearance interval counter, which would have to be performed on an every transfer cycle basis, may be performed less frequently, i.e., at intervals several times longer than the transfer cycle (depending on an update period of the update timing generating means), when a required transfer rate is low, while the processing remains unchanged when a required processing rate is high. It is therefore possible to multiplex the monitoring processing for a large number of streams while maintaining a monitoring accuracy in accordance with a processing rate of interest.
According to a fifth aspect of the present invention, a processing rate monitoring apparatus comprises (1) event detecting means for notifying a monitored stream corresponding to an event appearing on a transmission path every transfer cycle, (2) a plurality of appearance number counters each disposed for counting the number of events appearing within a monitoring period for a corresponding monitored stream, (3) a plurality of time counters each disposed for measuring a monitoring period for a corresponding monitored stream, where each of the time counters is responsive to each corresponding update timing signal input thereto to increment a count value, (4) a plurality of update timing generating means each corresponded to one or a plurality of the time counters for supplying an update timing signal each generated at different periods to a time counter placed in a corresponding relationship therewith, and (5) determining means, operable each time the lapse of a monitoring period is notified thereto from a corresponding time counter, to compare a count value of an appearance number counter indicating the number of newly counted packets within a current monitoring period with an allowed value for the number of appearing events calculated in consideration of an output period of the update timing and a processing rate of a monitored stream to determine the presence or absence of processing rate violation in the current monitoring period.
As a consequence, similarly to the fourth feature, the updating of the appearance interval counter, which would have to be performed on an every transfer cycle basis, may be performed less frequently, i.e., at intervals several times longer than the transfer cycle (depending on an update period of the update timing generating means), when a required transfer rate is low, while the processing remains unchanged when a required processing rate is high. It is therefore possible to multiplex the monitoring processing for a large number of streams while maintaining a monitoring accuracy in accordance with a processing rate of interest.
According to a sixth aspect of the present invention, a processing rate monitoring apparatus comprises (1) event detecting means for notifying a monitored stream corresponding to an event appearing on a transmission path every transfer cycle, (2) a plurality of queue means each for forwardly feeding one or a plurality of identification information registered in an arbitrary step at inherent transfer periods, and for notifying the next event arrival scheduled timing, based on identification information output from a final step, for a monitored stream corresponding to the identification information, (3) a plurality of scheduled timing passage determining flag holding means, each operable when notification of event arrival scheduled timing is detected, to set a corresponding flag and holding the state of the flag at a stage prior to detection of a corresponding event, (4) determining means, operable each time one transfer cycle has elapsed, to determine whether or not an event of a corresponding monitored stream is detected for each of monitored streams and whether or not the passage of the next event arrival scheduled timing is notified from a corresponding queue, and to determine the presence or absence of processing rate violation of a processing rate in a current monitoring cycle from the state of the flag held in a corresponding scheduled timing passage determining flag holding means when any affirmative determination is recognized.
As a consequence, the determination as to the presence or absence of processing rate violation can be made on the basis of previously calculated next event arrival prediction timing. Additionally, in this event, the event arrival prediction timing can be set in accordance with a transfer period inherent to a corresponding queue means and a registered position of the identification information to a step, thereby making it possible to simultaneously realize a consistent monitoring accuracy and a reduction in processing frequency.
According to a seventh aspect of the present invention, a processing rate monitoring apparatus comprises (1) event detecting means for notifying a monitored stream corresponding to an event appearing on a transmission path every transfer cycle, (2) a plurality of queue means each for forwardly feeding one or a plurality of identification information registered in an arbitrary step at inherent transfer periods, and for notifying the next event arrival scheduled timing, based on identification information output from a final step, for a monitored stream corresponding to the identification information, (3) fluctuation tolerance value holding counters each for holding a fluctuation tolerance value for the occurrence of a processing rate violation determining cycle allowed to a corresponding monitored stream, (4) determining means, operable each time one transfer cycle has elapsed, to determine whether or not an event of a corresponding monitored stream is detected for each of monitored streams and whether or not the passage of the next event arrival scheduled timing is notified from a corresponding queue, and to determine the presence or absence of processing rate violation over a plurality of monitoring cycles by determining whether or not a count value of the fluctuation tolerance value holding counter is larger than a predetermined threshold value when an event is detected before the next event arrival scheduled timing passes.
As a consequence, the determination on the presence or absence of processing rate violation can be realized as determination as an average rate over a plurality of monitoring cycles rather than in a monitored cycle basis, so that this is advantageously applied for monitoring a processing rate when events occur in a burst manner.